(Fair Value Of Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Mar. 31, 2019 |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Accrued Liabilities, Fair Value Disclosure | $ 35 | $ 136 |
Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Total assets at fair value | 1,910 | 3,032 |
Total liabilities at fair value | 49 | 12 |
Significant Other Observable Inputs (Level 2) | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Total assets at fair value | 1,677 | 765 |
Total liabilities at fair value | 9 | 16 |
Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Total assets at fair value | 0 | 0 |
Total liabilities at fair value | 0 | 136 |
Short-term investments | Significant Other Observable Inputs (Level 2) | U.S. agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 8 | |
Short-term investments | Significant Other Observable Inputs (Level 2) | Debt Security, Government, Non-US [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 48 | |
Short-term investments | Significant Other Observable Inputs (Level 2) | Asset-backed Securities [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Asset-backed securities | 281 | |
Short-term investments | Significant Other Observable Inputs (Level 2) | Certificates of Deposit [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 43 | |
Short-Term Investments And Cash Equivalents | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 459 | 294 |
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Corporate bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 837 | 327 |
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | U.S. agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | | 57 |
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 438 | 233 |
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Debt Security, Government, Non-US [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | | 58 |
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Asset-backed Securities [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Asset-backed securities | | 55 |
Short-Term Investments And Cash Equivalents | Significant Other Observable Inputs (Level 2) | Certificates of Deposit [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | | 2 |
Cash Equivalents | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Bank Time Deposits [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Cash equivalents | 85 | 23 |
Cash Equivalents | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Cash equivalents | 1,352 | 2,704 |
Other Current Assets and Other Assets [Domain] | Significant Other Observable Inputs (Level 2) | Foreign currency derivatives | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Foreign currency derivatives, assets | 22 | 33 |
Other assets | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Deferred compensation plan assets | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Deferred compensation plan assets | 14 | 11 |
Accrued And Other Current Liabilities [Member] | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Contingent consideration | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Accrued Liabilities, Fair Value Disclosure | 35 | |
Accrued And Other Current Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Contingent consideration | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Accrued Liabilities, Fair Value Disclosure | | 136 |
Accrued and Other Current Liabilities and Other Liabilities | Significant Other Observable Inputs (Level 2) | Foreign currency derivatives | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Foreign currency derivatives, liabilities | 9 | 16 |
Other liabilities | Quoted Prices In Active Markets For Identical Financial Instruments (Level 1) | Deferred Compensation Plan Liabilities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Deferred compensation plan assets | 14 | 12 |
Fair Value | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Total assets at fair value | 3,587 | 3,797 |
Total liabilities at fair value | 58 | 164 |
Fair Value | Short-term investments | U.S. agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 8 | |
Fair Value | Short-term investments | Debt Security, Government, Non-US [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 48 | |
Fair Value | Short-term investments | Asset-backed Securities [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Asset-backed securities | 281 | |
Fair Value | Short-term investments | Certificates of Deposit [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 43 | |
Fair Value | Short-Term Investments And Cash Equivalents | Corporate bonds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 837 | 327 |
Fair Value | Short-Term Investments And Cash Equivalents | U.S. Treasury securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 459 | 294 |
Fair Value | Short-Term Investments And Cash Equivalents | U.S. agency securities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | | 57 |
Fair Value | Short-Term Investments And Cash Equivalents | Commercial paper | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | 438 | 233 |
Fair Value | Short-Term Investments And Cash Equivalents | Debt Security, Government, Non-US [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | | 58 |
Fair Value | Short-Term Investments And Cash Equivalents | Asset-backed Securities [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Asset-backed securities | | 55 |
Fair Value | Short-Term Investments And Cash Equivalents | Certificates of Deposit [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Available-for-sale of securities | | 2 |
Fair Value | Cash Equivalents | Bank Time Deposits [Member] | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Cash equivalents | 85 | 23 |
Fair Value | Cash Equivalents | Money market funds | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Cash equivalents | 1,352 | 2,704 |
Fair Value | Other Current Assets and Other Assets [Domain] | Foreign currency derivatives | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Foreign currency derivatives, assets | 22 | 33 |
Fair Value | Other assets | Deferred compensation plan assets | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Deferred compensation plan assets | 14 | 11 |
Fair Value | Accrued And Other Current Liabilities [Member] | Contingent consideration | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Accrued Liabilities, Fair Value Disclosure | 35 | 136 |
Fair Value | Accrued and Other Current Liabilities and Other Liabilities | Foreign currency derivatives | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Foreign currency derivatives, liabilities | 9 | 16 |
Fair Value | Other liabilities | Deferred Compensation Plan Liabilities | | |
Fair Value, Balance Sheet Grouping, Financial Statement Captions | | |
Fair value, Deferred compensation plan assets | $ 14 | $ 12 |